The present invention relates to a method of and apparatus for controlling the feeding rate of fuel fed into an internal combustion engine during starting and for a period of time after starting of the engine.
In an internal combustion engine of the electronic fuel injection control type using fuel injection valves, or of the electronic carburetor control type using an electrically controlled carburetor, an engine starting enrichment operation for additionally increasing the fuel feeding rate during cranking (starting) is executed. After starting, the above additional increment of the fuel feeding rate is decreased in accordance with the lapse of time. The above additional increment during starting is determined depending upon the warm-up condition of the engine.
According to the prior art, the above additional increment during starting and after starting is determined quite independently of the rotational speed of the engine. Therefore, if the rotational speed of the engine changes immediately after starting due to racing, good operation characteristics of the engine are not often obtained. In a case where the above-mentioned additional increment is selected to be an optimum value at a low rotational speed, the air-fuel mixture becomes too rich at high rotational speed. Accordingly, the rotational speed is not smoothly increased, causing the engine to respond sluggishly. Furthermore, the spark plug becomes clogged and fuel consumption is increased. Contrary to this, if the additional increment is selected to be an optimum value at a high rotational speed, the air-fuel mixture becomes too lean at a low rotational speed. Accordingly, the engine will backfire and respond sluggishly. Particularly, since the above-mentioned additional increment of the fuel feeding rate during starting and after starting is set to a considerably greater value than at other times, the operation characteristics are greatly influenced by this increment.